U.S. Sen. Lincoln D. Chafee (R-R.I.)has asked members of a congressional committee to reject a last-minute amendment that could kill a planned wind farm off the coast of Cape Cod.

The amendment, proposed by Rep. Don Young, D-Alaska, to a bill that provides funding for the Coast Guard, would prohibit any offshore wind project from being constructed within 11/2 nautical miles of a shipping lane or ferry route. Young has expressed concern that without such a buffer zone, the wind-turbine towers could pose a hazard to marine traffic.

The project proposed by Cape Wind Associates, a Boston firm, would comprise 130 giant wind turbines about 6 miles off Cape Cod, in Nantucket Sound. Some of the towers would stand about 1,500 feet from a ferry route, Cape Wind Associates said.

"I urge you . . . to reject the proposed language," Chafee wrote on Monday to four Senate colleagues who sit on the Coast Guard Reauthorization Conference Committee, which is considering the measure.

"This provision, if added, will be devastating to an ongoing renewable wind energy project that is very valuable to Rhode Island and to greater New England."

Young voiced his concerns about safety in a five-page letter to colleagues on the conference committee, which he chairs.

"No one debates that America must encourage the development of alternative energy sources like offshore wind," he said in the Feb. 15 letter.

"But we need to set standards for such facilities before we move forward."

Young said that a British study of wind-power facilities "reveals that offshore wind facilities seriously disrupt basic navigation, increasing collision and pollution risk."

He said there is a "zone of extreme caution" that extends 1.5 nautical miles to 2 nautical miles from a wind turbine in which the device interferes with radar.

Young's proposed amendment has mobilized Cape Wind Associates, as well as project supporters, who say that the marine safety concerns have already been studied and addressed by Coast Guard reviews. They contend that Young has mischaracterized the British study.

"The Coast Guard has been studying this project for four years," said Jim Gordon, president of Cape Wind Associates, in a telephone interview yesterday. "The Army Corps of Engineers is also a cooperating agency. . . . Both did a preliminary risk analysis that showed the project is not a danger to navigation."

Gordon and other supporters said they are alarmed about the way Young introduced his amendment, describing it as underhanded attempt to kill the project.

The amendment did not come through normal channels. The Coast Guard funding bill had already been passed, without the Young provision, by both the House and Senate.

He has proposed amending it as part of the process by which the House and Senate are supposed to reconcile any differences they have with the versions each other have passed.

New provisions are not usually added at the committee stage, as neither the House nor the Senate as a whole will have a chance to discuss or debate such language. They will vote only to accept or reject the final bill that comes out of the committee.

Sen. John Kerry, D-Mass., issued a statement on Friday denouncing the proposed amendment.

"The Young Amendment is an insult to Americans who care about good government. I oppose this backdoor amendment to the Coast Guard Authorization Bill which -- if passed -- will derail offshore wind projects across the nation."

In his letter, Chafee said Young's measure is not the proper way to address marine-safety issues associated with wind turbines.